Electrosurgery is a form of surgery in which living body tissue is removed or destroyed by heat generated by an alternating high frequency current. A variety of systems for supplying the current have been developed. Most of them utilize an active and an indifferent electrode. The indifferent electrode is often a large metal plate which is placed on the leg, arm or back of the patient.
The high frequency current radiates through the tissues from the site of tissue contact of the small active electrode toward the larger indifferent electrode, then back to a power oscillator of an electrosurgical unit (ESU), and back again to the site of tissue contact of the small electrode, in a continuing radiating cycle. In this manner, the current is not evenly dispersed but instead attains a density or concentration at the site of the small electrode tissue contact that is great enough to produce cellular destruction, known as electrosurgery.
The active electrode may have a wide variety of shapes such as a needle or blade for cutting, or a wire loop for scraping.
When touched by the active electrode, tissue is disintegrated, but the heat generated does not penetrate the body deeply. Thus, the active electrode acts as a scalpel with the advantage that in the process of cutting, small blood vessels are sealed by the heat thereby reducing bleeding.
A number of electrosurgical instruments have been developed and used wherein an active electrode is attached to an insulated handle and a high frequency current is applied thereto from an electrosurgical current generator. Electrosurgical instruments found to be particularly safe and effective for surgical applications are those which incorporate finger actuated switches, those which allow for readily interchangeable electrodes, those which are water resistant, and those which are thin and properly balanced for close surgical use where a certain "feel" is necessary for the surgeon to properly use the instrument. An instrument such as the aforedescribed one is commonly referred to as an "electrosurgical pencil", particularly in view of its slenderness, and shape which resembles a pencil. Other names by which such an instrument is known include "hand held electrode holder" or "hand held, electrosurgical electrode holder", or "finger actuated electrosurgical electrode holder". Examples of finger actuated, electrosurgical electrode holders are described in United States Letters Patent Nos. 4,034,761 or 3,801,766 or 4,112,950 or 4,170,234.
A variation of such an instrument is one which is actuated by a foot controller rather than finger actuated switches. This latter variation is often referred to as a "foot actuated, electrosurgical electrode holder".
A more recent development in hand held, surgical electrode holders as described in copending U.S. Application Serial No. 872,166, filed 06/09/86 now U.S. Patent No. 4,688,569, issued Aug. 7, 1984, is that of a finger actuated electrosurgical electrode holder incorporating a light source such as a lamp for the purpose of illuminating the region of surgery. Such illumination is provided by means of an elongated fiber optic photoconductive device which extends generally longitudinally within the holder's active electrode, and which communicates in the holder with a light source such as a lamp.
From the teachings of U.S. Application Serial No. 872,166 one can readily appreciate how a similar light illuminating means can be incorporated into a foot actuated electrosurgical electrode holder as opposed to a finger actuated electrosurgical electrode holder.
Whether the instrument is actuated by finger switches or by foot control switches, if it incorporates a lamp means to provide localized illumination to the region of surgery, it can be referred to as a "lighted, hand held, electrosurgical electrode holder".
One object of this invention is to provide an adapter than can electrically connect to the lighted, hand held, electrosurgical electrode holder, and also to an ESU that is normally compatible with a non-lighted hand held electrosurgical electrode holder, and which can enable the electrosurgical current generator to light the lamp in the holder while at the same time permitting current for cutting (cut current) or current for coagulating (coag current) to pass through the holder's active electrode. That is, it is an object of the invention to provide a lighted, hand held, electrosurgical electrode holder which can also exactly duplicate any hand held, non-lighted surgical electrode holder.
Another object of this invention is to provide a means for delaying lamp shut-off, in order to enable the surgeon to inspect his region of surgery either prior to or following surgery.
Another object of this invention is to provide a means of insulating a hand held electrosurgical electrode holder from 60 H.sub.z leakage current.
Another object of this invention is to provide a means of isolating the active electrode in the holder from its switches, thereby permitting low voltage, low current, low cost, small switches to be used.
The foregoing and the objectives, features and advantages will be more apparent in view of the following detailed description of exemplary preferred embodiments, when taken in conjunction with the accompanying drawings.